<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
        "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <title>Title</title>
    <style rel="stylesheet" type="text/css">
        h1 {
            /*font-size: 30px;*/
            /*width: 10%;*/
            /*background-color: red;*/
            /*color: blue;*/
            /*border: yellow;*/
        }
        .outer {
            /*边界:大小4 固定 黑色*/
            border: 5px solid black;
        }

        .box {
            /*填充*/
            /*padding: 10px;*/
            /*宽度*/
            /*width: calc(90% - 30%);*/
            /*background-color: rebeccapurple;*/
            /*color: white;*/
        }
        .box2 {
            /*margin: 30px;*/
            /*width: 100px;*/
            /*height: 100px;*/
            /*background-color: rebeccapurple;*/
            /*transform: rotate(0.8turn);*/
            /*background-image: url("https://timgsa.baidu.com/timg?image&quality=80&size=b9999_10000&sec=1574241110471&di=4cf1567c69a3a89d76a14300c217dff9&imgtype=0&src=http%3A%2F%2Fb-ssl.duitang.com%2Fuploads%2Fitem%2F201208%2F30%2F20120830173930_PBfJE.jpeg");*/
            /*color: rgb(255, 255, 255);*/
        }
        body {
            /*background-color: pink;*/
        }
        @media (min-width: 30em) {
            body {
                /*background-color: blue;*/
            }
        }
        body {
            /*padding: 10px 15px 0px 5px;*/
            /*padding-top: 10px;*/
            /*padding-right: 15px;*/
            /*padding-bottom: 15px;*/
            /*padding-left: 5px;*/

            /*background: red url("http://1.jpg") 1000px 100px repeat-x fixed;*/
            /*background-color: red;*/
            /*background-image: url("http://1.jpg");*/
            /*background-position: 10px 10px;*/
            /*background-repeat: repeat-x;*/
            /*background-scroll: fixed;*/
        }
    </style>
</head>
<body>
    <h1>This is heading 1.</h1>
    <div class="outer">
        <div class="box">
            The inner box is 90% - 30px.
        </div>
    </div>

    <div class="box2">
        wusd
    </div>
</body>
</html>
